Growth kinetics and mechanism of the initial oxidation of Al-based Al–Mg alloys

The relationship between the growth kinetics and the local chemical states of Al, Mg and O ions in ultrathin (<3 nm) oxide films grown on Al-based Al–Mg substrates at T = 300–610 K was established by ellipsometry and XPS. At T ⩽ 385 K, an Al-oxide film of near-limiting thickness (∼1 nm) is formed, which exhibits interfacial and bulk-like states for the Al cations. At T > 385 K, continued growth is realized by the preferential oxidation of interfacially segregated Mg, resulting in the sequential appearance of interfacial and bulk-like states for the Mg cations.